title: Structure of electron-capture dissociation fragments from charge-tagged peptides probed by tunable infrared multiple photon dissociation.
abstract: In this study, we propose the first spectroscopic structural characterization of c-type ions produced by ECD of a peptide. The structure of c-type ions formed by electron capture dissociation and the overall mechanism leading to their formation are still a question of debate. Depending on the mechanism, c-type ions have been proposed to have either an enol-imine structure (-C(OH)NH) or an amide one (-C(O)-NH2). Since these ions are isomeric, mass spectrometry only cannot discriminate between them, but infrared spectroscopy can bring experimental evidence and help determine which scheme is operative. Using the coupling between a tunable free electron laser and a FT-ICR mass spectrometer, we show that c-type ions have an amide structure, characterized by an IR signature of the C=O stretch at 1731 cm(-1). This result is particularly interesting from the perspective of the elucidation of the ECD mechanism.
authors.affiliation: Laboratoire des Mécanismes Réactionnels, Department of Chemistry, Ecole Polytechnique and CNRS, 91128 Palaiseau, France.
authors.forename: Gilles
authors.initials: G
authors.lastname: Frison
authors.forename: Guillaume
authors.initials: G
authors.lastname: van der Rest
authors.forename: Frantisek
authors.initials: F
authors.lastname: Turecek
authors.forename: Thierry
authors.initials: T
authors.lastname: Besson
authors.forename: Joël
authors.initials: J
authors.lastname: Lemaire
authors.forename: Philippe
authors.initials: P
authors.lastname: Maître
authors.forename: Julia
authors.initials: J
authors.lastname: Chamot-Rooke
mesh_terms: D005583:Fourier Analysis; D013058:Mass Spectrometry / Q000379:methods; D008958:Models, Molecular; D010455:Peptides / Q000737:chemistry*; D017785:Photons; D013055:Spectrophotometry, Infrared / Q000379:methods*
chemical_list: D010455:Peptides